Starter bar having a frangible coupling

ABSTRACT

This is a detachable starter bar coupling in which a head member is detachably connected to one end of a continuous casting starter bar. The connection is made by means of a bolt having a reduced section near its midpoint so that the application of a preselected amount of force on the coupling will cause the bolt to break and the head to detach from the starter bar. The head is provided with a projecting bolt at one end thereof which is inserted in the continuous casting mold in order to be embedded within the cast strand as it solidifies.

United States Patent [72} Inventor Calvin C. Williamson Costa Mesa,Calif. 21 1 Appl. No. 771,822 [22] Filed Oct. 30, 1968 [45] PatentedJuly 20, 1971 [73] Assignee Soule Steel Company San Francisco, Calif.

[54] STARTER BAR HAVING-A FRANGIBLE COUPLING 4 Claims, 5 Drawing Figs.

[52] US. Cl 164/274, 64/28, 85/61, 164/282 [51] Int. Cl 822d 11/08 [50]Field of Search 164/274, 282, 283; 64/28; 85/61; 285/2, 3

[56] References Cited UNITED STATES PATENTS 490,313 1/1893 Schlickeysen64/28 2,085,074 6/1937 Boyles 85/61 UX Primary Examiner-R. SpencerAnnear Attorney-Townsend and Townsend ABSTRACT: This is a detachablestarter bar coupling in which a head member is detachably connected toone end of a continuous casting starter bar. The connection is made bymeans of a bolt having a reduced section near its midpoint so that theapplication of a preselected amount of force on the coupling will causethe bolt to break and the head to detach from the starter bar. The headis provided with a projecting bolt at one end thereof which is insertedin the continuous casting mold in order to be embedded within the caststrand as it solidifies.

STARTER BAR HAVING A FRANGIBLE COUPLING This invention relates tocontinuous casting apparatus and, more particularly. to a detachablecoupling head for continuous casting starter bars. While the continuouscasting art can be considered to date back to the time of Bessemer,continuous casting of steel on a commercial basis is of comparativelyrecent development. The invention of the principle of casting acontinuous strand by means of a curved, reciprocating mold bySchneckenburger (US. Pat. No. 2,947,075) revolutionized the industry.Schneckenburger describes the use of either a curved, solid starter bar,or a starter bar made up of comparatively short, bent parts. As is wellknown, the starter bar is inserted into the bottom of the flow throughmold in order to seal the bottom of the mold and permit the molten steelor other metal to begin to solidify prior to the formation of thecontinuous cast strand. If an articulated starter bar is utilized, thatis a bar having a number of detachable sections, it is comparativelyeasy to detach the starter bar sections individually as the bar movesdownward from the mold leaving only a corn paratively short piece firmlyattached to the strand as the strand is fed from the mold.

In the usual continuous casting apparatus utilizing a curved mold,straightener rolls are located at the point at which the curved strandis travelling in a horizontal direction. The straightener rollsstraighten the curved strand to permit the strand to move horizontallyalong a table so that individual billets may be cut from the strand. Inthose cases in which a solid, curved starter bar is utilized, theproblem of disconnecting the starter bar from the leading edge of thecast strand is more difficult. Sections of the starter bar cannot beremoved since the bar would in such a case be destroyed. Thus, somequick disconnect coupling is necessary to permit the curved, solid barto be disconnected from the cast strand.

The present invention was designed to permit a solid curved starter barto be readilyattached to the continuously cast strand and as readilydetached in order to permit the starter bar to be removed from themachine and reutilized for subsequent casting runs.

This is accomplished in the present invention by utilizing a detachablecoupling in which a coupling member has a projection thereon which maybe cast into the strand, the coupling member being fastened to thestarter bar by means of a severable fastener. This fastenerwill breakupon the application of a preselected amount of force, which will causerelative movement of the starter bar and the cast strand. This relativemovement may cause the severable fastener to break in shear or intension. The specific choice will depend upon the construction of thecontinuous casting machine and the means used for changing the directionof the cast strand.

In the present invention a severable fastener is utilized so that thecoupling member will be positively fastened to the starter bar until apreselected amount of force on the order of 2,000 to 3,000 pounds isapplied. Thus, there will be no opportunity for accidents to occurshould the coupling head accidentally become detached from the starterbar. It should also be noted that when the coupling head is fastened tothe starter bar the bar may be moved into position to seal the bottom ofthe mold and the casting cycle begun without the necessity for anyfurther adjustments or steps until the fastener is severed uponseparation of the starter bar from the cast strand.

In continuous casting, m'ost molds are reciprocated in order to reducethe sticking of the cast strand skin to the mold walls. Thereciprocation of the mold and the occasional sticking of the strandcauses jerky movement of the strand. As a result it has been found thata positive connection of the coupling member to the starter bar isrequired to preclude the accidental disconnection of the starter barfrom the strand. This positive connection is made in the presentinvention by means of a severable fastener which positively connects thecoupling member to the starter bar until sufficient force is appliedadjacent the coupling member to break the fastener.

IN Tl IE DRAWING FIG. I is an elevation showing the detachable starterbar coupling connected to the' cast stran-d as the strand begins toleave the casting mold;

FIG. 2 is a detail of the straightener rolls showing the separation ofthe starter bar from the coupling head attached to the cast strand;

FIG. 3 is an enlarged plan view of the coupling head attached to one endof the starter bar;

FIG. 4 is a sectional view taken along line 4-4 in FIG. 3; and

FIG. 5 is a detail of the severable bolt utilized to hold the couplinghead to the end of the starter bar.

Referring now more particularly to the drawing in which the samereference characters refer to corresponding parts in each of the severalviews, the general arrangement of the starter bar, coupling head andcasting apparatus is shown in FIG. I. The starter bar 10 is made up of anumber of comparatively short, curved sections 12 joined together bymeans of pins 14. The section 16 of the starter bar closest to thecasting is formed at the end thereof in any conventional manner tointerlock with the coupling head 18. A hole 20 is bored through theendof the starter bar 16 and the coupling head 18 with counterbores 22at either end of the holes so that a bolt 24 may be used to fasten thehead and bar together. The head 26 and the nut 28 fit within thecounterbores 22 so that they are fully recessed within the surfaces ofthe starter bar and coupling head. The coupling bolt 24 has a notchedportion 30 at approximately its midsection the depth of the notchpreselected so that the bolt will break upon the application'of between2,000 and 3,000 pounds of axial load.

The coupling head has a drilled and tapped hole 32 therein toaccommodate a headed-bolt 34 which serves to anchor the head 18 to thecast strand. I

At the commencement of the cast the starter bar 10 with the couplinghead 18 bolted to it by means of the severable bolt 24 is moved intoposition along the roller apron indicated in FIG. I by the plurality ofrollers 36. The coupling head and the starter bar have dimensionsapproximately equal to those of the inside of the flow-through mold 38.These will also be dimensions of the cast strand 40. The head 35 ofanchor I 34 extends into the inside of mold 38 and after the molten Isteel has been poured into the mold the head 35 will become embeddedwithin the leading tip 42 of the cast strand 40. When the castingprocess commences the starter bar 10 is slowly withdrawn along theroller apron drawing the cast strand 40 with it. The cast strandcontinues to be withdrawn until the tip 42 of the cast strand reachesthe straightener rolls 44 which are located at a point at which the caststrand is approximately tangent to a horizontal path. The straightenerrolls 44 when in the raised position as is shown in FIG. 1 will permitthe starter bar to continue on the generally arcuate path to a storagefacility 46 within which the bar may be held until the beginning of thenext casting cycle.

When the starter bar reaches the position at which the end section 16 ofthe starter bar is located as shown in FIG. 2, just past thestraightener rolls, the straightener rolls are moved by powerfulhydraulic cylinders or other means (not separately shown) downward fromthe position shown by the broken lines in FIG. 2 to the position atwhich they are shown in FIG. 2. The application of the 'force ofapproximately 2,000 to 3,000 pounds will force the tip 42 of the caststrand, together with the coupling head 18 which is firmly attached tothe tip, downward thus breaking the bolt 24' which has previouslyfastened the coupling head 18 and the end section 16 firmly together.After the coupling head 18 has been detached from the starter bar by thebreaking of bolt 24, the cast strand is straightened by continued actionof the straightener rolls 44.

The strand 40 passes horizontally along the horizontal roller table 48to the cutoff machine where the individual billets are severed from thestrand 40. The coupling head 18 may be removed from tip 42 of the caststrand by unscrewing the head from bolt 34. A replacement bolt 34 maythen be inserted into the head and the head fastened to the end of thestarter bar 16 by means ofa new severable bolt 24.

The coupling bolt 24 may, as an alternative to being notched, have ahold drilled through its shank or may have its cross section reduced inany suitable manner so that a preselected amount of force will cause thebolt to break at the reduced section.

lclaim:

1. In a starter bar device having a detachable head for a continuouscasting starter bar, said head having anchor means at one end thereoffor insertion into the continuous casting mold to permit solidificationof thecast metal of the strand about said anchor means, the other end ofthe head formed to engage cooperating portions of an end of the starterbar, the improvement comprising: a frangible connector transverselythrough said other end of said head for positively holding the headattached to the cooperating end of the starter bar until the applicationof a substantial preselected amount of force to break the connector andseparate the head from the starter bar end.

2. The detachable head of claim 1 wherein the starter bar end has a boretherethrough for accepting a frangiblebolt and said bore has acounterbored recess for receiving the bolt end so that the bolt is belowthe starter bar surface. g I

3. The detachable head of claim 1 wherein the head has a boretherethrough for accepting a frangible bolt and said bore has acounterbored recess for receiving the bolt end so that the bolt is belowthe detachable head surface.

4. The detachable head of claim 1 wherein the frangible connectorcomprises a bolt having a reduced cross section, the area of said crosssection being sufficient to fasten the head to the starter bar duringinitial casting operation but permitting separation of the head from thestarter barby breakage of the bolt at the reduced cross section upon theapplication of a substantial preselected amount of force.

1. In a starter bar device having a detachable head for a continuouscasting starter bar, said head having anchor means at one end thereoffor insertion into the continuous casting mold to permit solidificationof the cast metal of the strand about said anchor means, the other endof the head formed to engage cooperating portions of an end of thestarter bar, the improvement comprising: a frangible connectortransversely through said other end of said head for positively holdingthe head attached to the cooperating end of the starter bar until theapplication of a substantial preselected amount of force to break theconnector and separate the head from the starter bar end.
 2. Thedetachable head of claim 1 wherein the starter bar end has a boretherethrough for accepting a frangible bolt and said bore has acounterbored recess for receiving the bolt end so that the bolt is belowthe starter bar surface.
 3. The detachable head of claim 1 wherein thehead has a bore therethrough for accepting a frangible bolt and saidbore has a counterbored recess for receiving the bolt end so that thebolt is below the detachable head surface.
 4. The detachable head ofclaim 1 wherein the frangible connector comprises a bolt having areduced cross section, the area of said cross section being sufficientto fasten the head to the starter bar during initial casting operationbut permitting separation of the head from the starter bar by breakageof the bolt at the reduced cross section upon the application of asubstantial preselected amount of force.